linux-kernel - Re: [PATCH 4/7] cpufreq: intel_pstate: Simplify code in intel_pstate_adjust_busy

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Date:	Tue, 10 Jun 2014 10:57:06 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Stratos Karafotis <stratosk@...aphore.gr>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Dirk Brandewie <dirk.j.brandewie@...el.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/7] cpufreq: intel_pstate: Simplify code in intel_pstate_adjust_busy_pstate

On 10 June 2014 02:30, Stratos Karafotis <stratosk@...aphore.gr> wrote:
> Simplify the code by removing the inline functions
> pstate_increase and pstate_decrease and use directly the
> intel_pstate_set_pstate.
>
> Signed-off-by: Stratos Karafotis <stratosk@...aphore.gr>
> ---
>  drivers/cpufreq/intel_pstate.c | 26 +++-----------------------
>  1 file changed, 3 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 3a49269..26a0262 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -588,21 +588,6 @@ static void intel_pstate_set_pstate(struct cpudata *cpu, int pstate)
>         pstate_funcs.set(cpu, pstate);
>  }
>
> -static inline void intel_pstate_pstate_increase(struct cpudata *cpu, int steps)
> -{
> -       int target;
> -       target = cpu->pstate.current_pstate + steps;
> -
> -       intel_pstate_set_pstate(cpu, target);
> -}
> -
> -static inline void intel_pstate_pstate_decrease(struct cpudata *cpu, int steps)
> -{
> -       int target;
> -       target = cpu->pstate.current_pstate - steps;
> -       intel_pstate_set_pstate(cpu, target);
> -}
> -
>  static void intel_pstate_get_cpu_pstates(struct cpudata *cpu)
>  {
>         cpu->pstate.min_pstate = pstate_funcs.get_min();
> @@ -695,20 +680,15 @@ static inline void intel_pstate_calc_scaled_busy(struct cpudata *cpu)
>  static inline void intel_pstate_adjust_busy_pstate(struct cpudata *cpu)
>  {
>         struct _pid *pid;
> -       signed int ctl = 0;
> -       int steps;
> +       signed int ctl;
>
>         pid = &cpu->pid;
>         intel_pstate_calc_scaled_busy(cpu);
>
>         ctl = pid_calc(pid, cpu->sample.busy_scaled);
>
> -       steps = abs(ctl);
> -
> -       if (ctl < 0)
> -               intel_pstate_pstate_increase(cpu, steps);
> -       else
> -               intel_pstate_pstate_decrease(cpu, steps);
> +       /* Negative values of ctl increase the pstate and vice versa */
> +       intel_pstate_set_pstate(cpu, cpu->pstate.current_pstate - ctl);
>  }

I am not very good at this driver but there is some obvious functional
change here. Earlier we used to pass
'cpu->pstate.current_pstate {-|+} steps' and now you are doing '-ctl' only
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